What is it?
In my knowledge, wallwisher is a website where you can create an open forum, or in this case, a wall,to allow the public or a particular group of audience to have some multimedia discussion for free! Also, it is totally user-friendly and steps to get it started are self-explanatory.

Here are some possible approaches to Wallwisher to facilitate teaching :
1.Since it allows anonymous posts, the teacher can ask the students to give criticism and suggestions without giving students any pressure.

2.Organize some nice warm-up activity like brainstorming if the classroom is fully equipped. The students can provide their ideas and make their own contributions simultaneously.

3.The students can ask any questions or share whatever they think useful related to a certain lecture on this particular wall and the teacher can answer them by posting a new sticky. What's more, sometimes what the students provide online may help the teacher better reflect on his or her teaching.

4.When assigning the class into groups, each group can have their own wall and all their discussion and research results can be shown online. The teacher can supervise several groups at the same time without the need to move around.

Limitations:
1. In my perspective, it only suits for groups less than 8 people, otherwise the screen will turn into a complete clutter if everyone performs actively.

2. Due to financial restrictions, not in every context the students have their own laptops.